Radiation stability of polymer pellicles

A method comprising:

• sealing a chamber with a pellicle membrane, the pellicle membrane dividing the chamber into first and second compartments, the chamber having an inflow opening in the first compartment and an outflow opening in the second compartment;
• and
• injecting a gas into the inflow opening, the gas penetrating the pellicle membrane to the outflow opening.

A method comprising:

• sealing a chamber with a pellicle membrane, the pellicle membrane dividing the chamber into first and second compartments, the chamber having a first inflow opening and a first outflow opening in the first compartment and a second inflow opening and a second outflow opening in the second compartment;
• and
• injecting a first gas into the first inflow opening and a second gas into the second inflow opening, the first and second gases having a permeability difference, the first gas penetrating the pellicle membrane to the second outflow opening.

An apparatus comprising:

• a pellicle being pre-baked at a predetermined temperature substantially below a glass transition temperature;
• and
• a chamber containing the pre-baked pellicle to purge the pellicle with an inert gas, the purged pellicle being radiated by a radiation at a wavelength.

An apparatus comprising:

• a chamber sealed with a pellicle membrane, the pellicle membrane dividing the chamber into first and second compartments, the chamber having an inflow opening in the first compartment and an outflow opening in the second compartment, the inflow opening receiving a gas, the gas penetrating the pellicle membrane to the outflow opening.

An apparatus comprising:

• a chamber being sealed with a pellicle membrane, the pellicle membrane dividing the chamber into first and second compartments, the chamber having a first inflow opening and a first outflow opening in the first compartment and a second inflow opening and a second outflow opening in the second compartment, the first and second inflow openings receiving first and second bases, the first and second gases having a permeability difference, the first gas penetrating the pellicle membrane to the second outflow opening.

An apparatus comprising:

• a pellicle frame having first and second ends to hold a pellicle membrane, the pellicle frame and the pellicle membrane forming a pellicle space;
• and
• inflow and outflow valves at ends of the pellicle frame to allow a purge flow to go through the pellicle space.